Dillsue

First screen shot looks fine with 8kw from your battery plus 4kw from the grid feeding a 12kw house load. We're you using that much at 18.43? If those figures are correct then it's hard to see how the CT clamps are the wrong way round

That's likely the width of their mid clamp which could well be 24mm

My HP isn't a CE pump but has lots of connections/functions that aren't particularly well documented so its an evolving process knowing what I need/want to connect. If CE specify a certain number of cores and there's no other signals that you may want in the future then run with what they suggest. On the other hand if there's other connections/functions that you may want to use in the future then pulling in a larger number of cores is going to make life easier to hook up additional signals in the future

Double check that 7 cores is enough bearing in mind that 7 core cable is usually 6 core plus earth. You can sleeve the earth if your really stuck but not best practice. I've just installed a second 7 core cable to pick up some setback signals but should have installed a 12 core cable from the outset!

At a guess I'd say our IntaKlean filter mesh is 2-4 times the surface area of the mesh in your picture, so my view would be that your strainer is potentially too small. Have you checked if there's one fitted internally in the HP? The Vaillant hydraulic schematic I've just looked at has a mag filter in the return leg from the CH

Where's your installer? Should he be explaining how he's designed/installed things and setting the system up for you??

I'm not sure what type of filtration Vailant specify but LG specify a magnetic filter which must be installed. As well as catching anything magnetic the IntaKlean one we have has a large fine mesh strainer. If Vailant specify a mag filter then you can bin the external Y strainer in your picture and get the correct filter installed. Our HP has a Y strainer fitted inside the HP casing which is rendered redundant by the mag filter, but worth checking your Vailant doesn't have an internal strainer as you can bin the external one if its got one internally.

In this context "their son" is anyone who doesn't understand what the regulation is for and inadvertently or intentionally removes the export limit without considering the implications. That's a potential spin off from by passing the regulation which was being hinted at

My mis understanding then. Originally you said 3 x AC coupled battery inverters connected in parallel which I took to mean they were all connected to the grid.

And if the person doing that was your neighbour and their son inadvertently reset the limit to max export that subsequently pushed the grid voltage up high enough to trip your PV would you be happy? If the same excess voltage tripped another neighbours medical equipment, would they be happy? It's all regulated for good reason and I'm sure you know whether it's right or wrong

You're understanding is correct

If you connect any generator to the grid, the DNO gets involved whether you intend to export or not. It's a legal requirement covered in the National Terms of Connection that everyone with a grid connection is signed up to via your electricity supply contract. If the generator is a PV inverter with a G98 cert you tell the DNO after you've connected it. Anything else you ask for permission BEFORE you connect regardless of whether you've set it to zero export. Eon won't have approved a system for export as only the ENA/DNO can do that. Eon may have agreed to buy any exported electricity

?? You suggested 3 G98 devices in parallel with 1 as master and retain the G98 certification which isn't possible.

My comments were on parallel wired G98 devices where they are all connected direct to the grid. If you are series wiring then it's only the final device connected to the grid that needs to meet the DNO specs

With more than 1 G98 device wouldn't you have moved into G99/G100 territory with the master inverter doing the G100 management??

What would you do if you had the G98/3.68kw export limit?? If that would make a difference to your plans then throw in a secondhand G98 inverter, get the DNO to make any mods needed to accommodate that and you've upped your export limit

Solid fence is a good start and I guess a nice sparky will do whatever you ask within the bounds of decency and electrical regs

Doesn't an existing fence count as property, as opposed to a free standing ground mounted array??

If it's a cage clamp connector that you open with a screwdriver, look down the open end and you'll see the clamp opening when you push the screwdriver in. They are crimpless connectors so just cut off the existing end, strip off 10-12mm of insulation and carefully slide the bunched strands into the opening checking there's no strands sticking out. Don't twist or crimp the stranded ends as they are intended to be squashed by the clamp to maximise the contact area....majorly important with cage clamp power connectors to max out the contact area but not so important with low power connections.

The panels will need mounting on something so there'll be a cost for that something, whatever it is. If the fence is a boundary between the OP and neighbours it's likely to need to be aesthetically pleasing and I doubt the neighbours would want to look at the back of PV panels. It's a Solaredge system so it won't work without SE optimisers. Cables will likely need managing. I'd be fairly confident there'll be more costs than just the panels and a spark??

Plus mounting rails, clamps, cable, conduit, optimisers. Mounted vertically will improve winter generation but total for the year will likely be lower than roof mounted at an angle. If you're bothered about £ROI then maybe run the generation through PVGIS, but if you've got £ to blow crack on and enjoy the novelty

Are the DNOs able to gain any meaningful peak generation info from domestic scale PV info when they never ask for details of the direction and inclination of installed panels??

?? @Pocster is likely on a 60-100amp supply so the cabling will carry 16amp easily. If it can carry 16amp for 1 sunny day it can carry it every day. I believe @Pocster has had extensive dialogue with his DNO over adding batteries so everything will almost certainly be specced right

Your grid connection will already be rated to carry 16amp export. Your inverter will push that out for hours on a sunny summers day so not a problem to do that every day, if you had enough sun

If your still running solaredge then you can add more panels up to the max number of optimisers....24 if it's an SE3680H you've got. You also need to keep under the max DC input which is likely double the inverter rating. DNO is only interested in the max the inverter will produce so adding panels won't increase that. If you're getting FIT then you need to notify your FIT payer of the addition. If youre thinking of building a fence with panels, remember that lots of fences eventually blow down and pretty much all wooden fences eventually succumb with rot. Climate change ain't gonna make future storms any less intense and likely the opposite so use battleship engineering